1. Field of the Invention
The present invention relates to a device for dissociating feed material occurring as mixed materials and a corresponding method.
2. Description of the Background Art
Mechanical process engineering has as its object the treatment and processing of starting materials into a final product. In view of diminishing primary raw materials, growing environmental awareness, and increasing cost pressures, it is becoming increasingly important to separate waste materials and products, which in this way reenter the product cycle as secondary raw materials.
In the recycling of waste materials and products, operators of applicable facilities are faced with huge challenges, since these materials are very different in size, form, and composition, so that reusable starting materials can only be produced from them with a great deal of effort. This is all the more true for materials and products occurring as mixed materials whose separation is especially difficult by nature. Some examples of such materials are: reclaimed lumber containing nails, screws, or other metal parts; plastic-jacketed electric cable with a metal core; used rubber tires with steel reinforcement; technical rubber parts; and electronic scrap. The goal of recycling in this context is always to extract the individual components of the mixed material as cleanly by type as possible, in order to be able to use them as a starting material for other manufacturing processes.
To this end, multistage processes and facilities are known that the feed material passes through in succession. The individual process stages here are composed of devices connected in series whose processing tools in each case are adapted to the particular nature of the feed material—in terms of size, form, and composition—produced by the device immediately upstream in the process. As a general rule, a size reduction is brought about in each stage by cutting devices. In this context, one or more components of the mixed material are removed from the feed material in each stage until finally, in the ideal case, the components of the mixed material have been separated completely from one another.
A dissociation and separation of the mixed materials can indeed be achieved with this process. The disadvantage, however, is the necessity for each processing stage to have a separate device, so that substantial financial disadvantages in terms of acquisition, maintenance, and operation must be tolerated.
From US 2006/0118671 A1 is known a device for recycling scrap tires with a horizontal rotor that is rotatably mounted within a housing. The rotor is equipped around its circumference with fragmentation tools that work together with stationary stator tools on the housing. Adjoining the stator tools in the rotor's direction of rotation is a continuous screen surface through which is drawn off the adequately broken up and fragmented feed material.
After the feed material has been fed from above, it is initially processed by being fragmented between rotor and stator tools and then by further dissociation, between the rotor surface and screen surface, of the material components combined in the mixed material. The constant design boundary conditions in the area of the processing zone result in a consistent processing of the feed material over the entire length of the screen. This has the result that such devices are suitable only for feed material whose form and size vary within narrow limits, for which reason this device is primarily appropriate for use within one stage of the above-described overall process.
A further disadvantage of such devices is the uneven wear over the screen length. It has been demonstrated that the wear of the screen surface is greatest in the area behind the stator knife, with the consequence that screens must be replaced solely because of the severe wear in that area, while sufficient reserves are still present in the end region. To increase the service life of the screens here, it is also known to turn the screens so that the section forming the screen end in the direction of rotation then forms the screen start after rotation of the screen. In this way, one obtains screens that are severely worn out from abrasion at the screen start and end while the central region exhibits only moderate signs of wear.